File Formats Our Hand and Finger Viewer Reads

Archive formats

If your scan came as one big compressed file, drop it directly into the viewer — we unpack it in your browser.

• ZIP — the most common format on hospital CDs and patient-portal downloads
• TAR — common for research datasets
• .tar.gz and .tgz — TAR + GZIP compressed

DICOM transfer syntaxes

The technical format used to encode pixel data inside a DICOM file. Our viewer decodes every common transfer syntax used by clinical scanners.

• Implicit VR Little Endian (1.2.840.10008.1.2)
• Explicit VR Little Endian (1.2.840.10008.1.2.1)
• JPEG Lossless (1.2.840.10008.1.2.4.70)
• JPEG Extended 12-bit (used by i-CAT dental CBCT)
• RLE Lossless
• 8-bit, 12-bit, and 16-bit pixel data
• MONOCHROME1 and MONOCHROME2 photometric interpretations

NIfTI (research / converted scans)

NIfTI (Neuroimaging Informatics Technology Initiative) is the format used by most research and post-processing tools. If you ran your scan through a pipeline like FreeSurfer or fastMRI, you likely have a NIfTI file.

• .nii — uncompressed NIfTI volume
• .nii.gz — GZIP-compressed NIfTI (most common)

What a hand and finger imaging study usually contains

Most hand referrals start with radiographs of a single digit rather than the whole hand. A finger series typically pairs a posteroanterior view with a true oblique and a strict lateral of that one digit, because overlapping bones on a whole-hand film hide exactly the fracture line or joint space a hand surgeon needs to see. When a skier's thumb or a suspected ulnar collateral ligament tear is on the table, the radiographer adds stress views of the thumb metacarpophalangeal joint, taken with gentle radial and ulnar stress to reveal instability that a resting film would miss. A dedicated finger series resolves far more subtle detail at the joint line than a single wide hand film ever will, which is why clinics keep ordering the narrower study even though it means more images to review.

Hand MRI follows the same narrow-field logic. A small surface coil wrapped around one or two digits produces thin axial, coronal, and sagittal proton-density fat-saturated series through the flexor and extensor tendons, the collateral ligaments, and the joint cartilage — detail that a body coil simply cannot resolve at this scale. When the question is broader, such as diffuse swelling or a suspected infection spreading across the hand, the radiologist instead images the whole hand in a single coil, trading some of that fine in-plane resolution for coverage of every digit and the carpometacarpal region in one pass. Complex metacarpal fractures and intra-articular phalanx fractures that need surgical planning are more often sent to hand CT, where thin isotropic slices let the surgeon see the fracture pattern from any angle before choosing hardware.

How a hand study usually reaches you

Hand studies are almost always small on disk, since the field of view rarely extends past the wrist crease. A finger or hand X-ray series is often only a few megabytes, and when several digits were imaged separately you may end up with three or four distinct series in the same folder instead of one combined study. Emergency departments increasingly deliver these through a patient portal as a single DICOM object per view rather than a full study package, so don't be surprised if a finger injury arrives as three individual files instead of a folder. Outpatient hand clinics still favor hospital CDs carrying a DICOMDIR index alongside the numbered image files, and referral centers frequently rebundle that same content into a ZIP archive before emailing it onward. Research and 3D-printing workflows for custom splints sometimes convert a hand CT into NIfTI instead, which drops the DICOM header but keeps the volume itself intact.

Slice thickness and 3D rendering for a hand study

A hand MRI on a small surface coil typically holds sub-millimeter in-plane resolution with roughly 2 millimeter slices over a single finger, which is excellent for reading soft tissue and ligament detail on the acquired plane but produces a stack too short and too thin in the slice direction to volume render convincingly — you get a crisp 2D read, not a rotatable digit. Hand CT behaves very differently: it's usually reconstructed at isotropic or near-isotropic voxel size specifically so a surgeon can rotate a metacarpal or phalanx fracture in any plane before fixation, and that isotropic geometry is what lets our 3D renderer build a clean bone model from it. A single PA hand radiograph sits at the opposite end entirely — it's one flat two-dimensional projection with no depth information at all, so it always displays as a still image, never a volume, no matter how it's exported.

Compatibility at a glance

Guides: private viewing and 3D rendering for hand studies

When a hand or finger study still won't open

A few hand studies still cause trouble in any browser-based viewer. The most common complaint isn't a broken file at all — it's discovering the wrong digit was imaged, which no viewer can fix; go back to the imaging center and ask specifically for a dedicated finger series of the correct digit rather than another wide hand film. Post- operative hands with K-wires, screws, or a fixation plate open normally, though dense metal can wash out the immediately adjacent bone on CT. If a portal only handed you a single DICOM file per view instead of a folder, that's expected for emergency exports — drop each file in individually and the viewer will still group them once loaded. And if what you have is really the disc's bundled Windows program rather than the image folder itself, look for the subfolder containing a DICOMDIR file and numbered slices and use that instead.